Relays are well known electromechanical devices for circuit switching and isolation and have widespread applicability in automotive applications. A typical automotive relay has an armature subassembly which is welded to the relay frame and is actuated between conducting and nonconducting positions responsive to electrical signals. The armature subassembly of a relay comprises a generally L-shaped contactor blade mounting an armature in the form of a plate element. The geometric configuration of the contactor blade can be critical to the performance of the relay and Kwapisz, U.S. Pat. No. 4,959,784 issued Sept. 25, 1990 entitled "Method and System for Adjusting Relay Armatures" (which is incorporated by reference) discloses a method and apparatus for adjusting the armature subassembly after it has been welded to the relay.
Of particular importance to the performance of a relay is the relay armature-frame gap. The relay armature-frame gap is the separation or air gap between the armature and the frame which is necessary to prevent mechanical binding during operation. In assembly, the armature is more or less "floating", being mounted to the distal end of the contactor blade and movable in one direction by a magnetic actuating force and in the other direction by the spring bias of the contactor blade. It is very important to the performance of a relay that an even or uniform gap be formed to prevent mechanical binding.
Previous apparatus and methods for assembling relays have not been entirely satisfactory in consistently producing a proper gap. From a manufacturing standpoint, improper gaps result in undesirable component performance or costly component rejection and/or repair.
Accordingly, it is an object of the present invention to provide a new and improved method and apparatus for relay assembly which achieves enhanced control of the formation of the relay armature-frame gap.
Another object of the invention is to provide such a method and apparatus which produces an even or uniform gap to prevent mechanical binding during the operation of the relay.
Another object of the invention is to provide such a method of assembly which is particularly adapted for automated assembly.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.
It has been found that the foregoing disadvantages of the prior art are overcome in a method of assembling a relay which includes positioning the armature subassembly so that the proximal end of the contactor blade is adjacent the upper wall of the relay frame and the armature is adjacent to the front edge of the frame. The distal end of the contactor blade is mechanically positioned and held against the relay subassembly so that the armature is aligned flush against the front edge of the frame. The proximal end of the contactor blade is held against the upper wall of the frame and the distal end of the contactor blade is then released to assume a rest position so that the armature and front edge forms an even gap before welding the proximal end of the contactor blade to the frame. Prior to releasing the distal end of the contactor blade, the proximal end of the contactor blade is released to relieve position-affecting stress on the contactor blade and then the proximal end is held against the upper wall in a manner so as to prevent stress on the contactor which would deleteriously affect the armature-frame gap.